This invention relates to a gas-blast circuit breaker having a plurality of serially arranged circuit breaking stations per pole. Each circuit breaking station has a gas-compressing arrangement formed of a piston-and-cylinder assembly, a movable contact, a stationary counter contact, as well as a movable nozzle of insulating material.
A gas-blast circuit breaker having, for the arc-extinguishing gas, a compressing arrangement formed of a stationary piston and a movable cylinder is described, for example, in U.S. Pat. application Ser. No. 881,719, now U.S. Pat. No. 4,211,904, issued July 8, 1980. During the circuit breaking operation, the cylinder is moved with respect to the stationary piston and thus the extinguishing gas in the compression chamber is compressed. In case such a circuit breaker is to be installed in a grounded metal housing, for the purpose of protecting the metal walls against arcs, the circuit breaker has to be additionally surrounded by a tube made of an insulating material. Such an insulating tube may also be needed in case a plurality of serially arranged circuit breaking stations per pole are provided, as described, for example, in U.S. Pat. application Ser. No. 758,870, now U.S. Pat. No. 4,105,880. In this circuit breaker structure, the insulating tube serves for the support of the stationary components of the circuit breaking stations.